Apparatus for allowing access to the interior of an automobile and/or starting controls without using a conventional key have long been known. These keyless systems typically require the entry of a proper sequence of key depressions through an array of switches, after which access to the automotive interior or access to the engine starting controls is allowed. These systems obviate the need for an authorized user of the automobile to carry keys to gain access. Some such systems can also serve a theft-deterrent function by causing an alarm to be produced if sufficiently many incorrect entrance signals are attempted by an unauthorized person who wishes to gain access to the automobile and/or engine starting controls. Such a system is disclosed by Hinrichs in U.S. Pat. No. 3,691,396. Other systems serving similar functions are disclosed by Ellsberg in U.S. Pat. No. 4,233,642, by Betton in U.S. Pat. No. 4,533,016, and by Cook et al in U.S. Pat. No. 4,545,343.
In most automotive keyless entry systems, it is possible for the vehicle owner to change the access sequence. However, because these system's do not provide a feedback signal to the user to indicate whether each switch actuation has been recognized by the entry system, it is possible that the access sequence can be inadvertently changed to an undesired and unknown sequence. Under these circumstances, it can be necessary for the automobile owner to get assistance from its manufacturer or a dealer in order to regain access, at the cost of significant inconvenience to the owner.
While those systems that allow access to engine starter controls (for example, activating a normal key-operated ignition/starter switch) may work well in automotive applications, they are not appropriate for controlling access to the controls of vehicles subject to greater lurching motions than a typical automobile. Such vehicles include off-road vehicles, and, most especially, powerboats. The fact that such vehicles are subject to motions that may lead to inadvertent actuation of engine controls, such as ignition, starter, and choke controls, makes it desirable to provide these vehicles with apparatus that prevents such inadvertent actuation. Furthermore, keyless sytems can provide a level of convenience to operators of these vehicles who do not wish to carry keys or who are subject to irretrievably losing such keys, e.g., into a body of water.
It is further desirable to have a keyless access system that significantly reduces the chance that an access sequence will be inadvertently changed to an unknown sequence.